The pulp is the connective tissue, nerves, blood vessels, and odontoblasts that comprise the innermost layer of a tooth.

Together the epithelial enamel organ and ectomesenchymal dental papilla and follicle form the tooth germ.

By virtue of their peptide content, they also play important functions in inflammatory events and subsequent tissue repair.

The A-Fibres, mainly of the A-delta type, are preferentially located in the periphery of the pulp, where they are in close association with the odontoblasts and extend fibers to many but not all dentinal tubules.

The C-Fibres typically terminate in the pulp tissue proper, either as free nerve endings or as branches around blood vessels.

They branch to form the subodontoblastic nerve plexus of Raschkow, which is separated from the odontoblasts by a cell-free zone of Weil.

As the dental pulp is a highly vascularised and innervated region of the tooth, it is the site of origin for most pain-related sensations.

The neurons enter the pulp cavity through the apical foramen and branch off to form the nerve plexus of Raschkow.

A healthy tooth is expected to respond to sensitivity testing with a short, sharp burst of pain which subsides when the stimulus is removed.

Unlike irreversible pulpitis, the pulp gives a regular response to sensibility tests and inflammation resolves with management of the cause.

If the condition is reversible, the pulp's pain response lasts a few seconds upon exposure to cold or hot.

This is due to its aetiology; inflammatory exudate can be quickly removed, e.g. through a large carious cavity or previous trauma that caused painless pulp exposure.

[18][6] As the names imply, these diseases are largely characterised by their symptoms: pain duration and location, and exacerbating and relieving factors.

Inputs include clinical tests (cold ethyl chloride, EPT, hot-gutta percha, palpation), radiographic analysis (peri-apical and/or cone-beam computed tomography) and others.

Thermal tests are subjective, and are therefore performed the compromised tooth and the adjacent and contralateral teeth, allowing the patient to compare them.

The empty root canal system is then obturated with gutta-percha (rubber material that acts as a pressure/pain reliever).

Teeth with pulp necrosis undergo a root canal or extraction to prevent further spread of the infection, which may lead to an abscess.

[21][22] Asymptomatic necrosis is non-responsive to thermal stimuli or electric pulp tests, leaving the patient unaware of the pathology.

hot or cold stimuli (using warm gutta-percha or ethyl chloride), or an electric pulp tester.

[23] Sequelae of a necrotic pulp include acute apical periodontitis, dental abscess, or radicular cyst and tooth discolouration.

[24] Untreated necrotic pulp may result in further complications, such as infection, fever, swelling, abscesses and bone loss.

[14] This sampling process is part of the normal immune response, as it triggers leukocytes from the circulatory system to adhere to endothelial cells lining blood vessels and then migrates to the site of infection for defence.

Macrophages can phagocytose bacteria and activate T cells, triggering the adaptive immune response that occurs in association with DCs.

[15] In the pulp, DCs secrete a range of cytokines that influence immune responses, and are key regulators of the infection defence.

BDs kill microorganisms by forming micropores that destroy membrane integrity and cause leakage of the cell content.

It has been recorded that pulpal calcifications can occur due to: Pulp stones usually consist of circular layers of mineralised tissues.

[32] A review suggested this was because the first molars are the first teeth to be located in the mandible (lower jaw) and have longer exposure to degenerative changes.

The hard and closed surroundings builds pressure inside the pulp chamber, compressing the nerve fibres and eliciting pain.

At this stage, the pulp starts to die, progressing to periapical abscess formation (chronic pulpitis).

The pulp undergoes a decrease in intercellular substance, water, and cells as it fills with collagen fibers.